Star drill



J. KOTT STAR DRILL April 9, 1946.

Filed March 14, 1944 [NVE/VTOR I Joy/v A ozr Patented Apr. 9, 1946 UNITED STATES PATENT OFFICE STAR DRILL John Kott, Portland, Oreg.

Application March 14, 1944, Serial No. 526,466

1 Claim.

This invention relates generally to drilling machines and particularly to a star drill.

The main object of this invention is to provide a drill especially adapted for use in drilling holes in concrete, stone, and similar materials with a minimum expenditure of time and energy.

'The second object is to produce a drill of the class described in which holes can be drilled in otherwise inaccessible places and without danger or injury to the person of the user.

A further object is to provide a drill of the class described which will never stick in the drilling operation and which will automatically turn out the material at the bottom of the hole as rapidly as the indentations are made therein.

I accomplish these and other objects in the manner set forth in the following specification as illustrated in the accompanying drawing, in which:

Fig. 1 is a side elevation of the device showing the drill entered into a slab of concrete which is shown in section.

Fig. 2 is a fragmentary longitudinal section through the device showing the operating handle in a depressed position.

Fig. 3 is a transverse section taken along line 3-3 in Fig. 2.

Fig. 4 is a bottom view of Fig. 2.

Referring in detail to the drawing, there is shown a tubular core I having a spiral slot ll formed therein. The lower end [2 of the core I!) is secured by means of a pin i3 to a chuck I4, into the lower end of which can be inserted the usual star drill bit 15, which is held by means of a set screw 16 or in any other convenient manner,

The core It is slidably placed within the sleeve ll, whose lower end I8 strikes against the chuck Hi when the sleeve I! is in a lowermost position. A disc [9 is placed across the upper end of the core l0 and has attached thereto a tension spring 29 Whose lower end is attached to a bolt 2|, on which is mounted a roller 22, which occupies the slot II. The bolt 2| projects through a hole 23 in the sleeve I1, and is locked by means of the nut 24. On the upper end of the sleeve I1 is mounted a T handle 25. .A rounded head 26 is placed on the top of the handle 25 and the shank 21 of the head 26 extends into the sleeve l1 and the pin 28 secures the members 25, 25 and 21 together.

The operation of this device is as follows:

When it is desired to drill a hole in concrete 29, it is only necessary to place the point 30 of the drill l 5 in the correct position and then to grasp the handle 25 with both hand and cause the sleeve H to reciprocate vigorously by moving the handle 25 downwardly, causing it to strike against the chuck M with force, and thereby impart the blow to the drill point 28.

Obviously while the sleeve I1 is descending it cannot rotate, by reason of the fact that the handle 25 is held by both hands and therefore it causes the drill l5 to rotate as the sleeve H descends. After the blow is struck, the rebound coupled with the tension of the spring 20 causes the handle 25 to move to the position shown in Fig. 1, after which the movement is repeated.

It can be seen that as the star drill cuts downwardly, it also cuts in a rotary fashion, making it very effective in this operation.

While I have thus illustrated and described my invention, it is not my intention to limit it to the precise form shown herein, but I do intend to cover all such forms and modifications thereof as fall fairly within the appended claim.

I claim:

A drill of the class described, consisting of a chuck for holding a star drill bit, a spirally slotted tubular core constituting an extension for said chuck, a sleeve slidably mounted on said tube adapted to stop against said chuck, said sleeve having a roller attached thereto disposed within said spiral slot, a T handle on aid sleeve whereby same may be reciprocated and whereby resistance may be offered against a turning movement, and a spring within said core adapted to urge said handle away from the point of said drill.

JOHN KOTT. 

